Next story in Death of bin Laden

Part of a damaged helicopter is seen lying near Osama bin Laden's compound on Monday, a day after U.S. Navy SEAL commandos killed the al-Qaida leader. Bin Laden was killed in the U.S. special forces assault on the Abbottabad, Pakistan compound, then quickly buried at sea, in a dramatic end to the long manhunt for the man who had been the guiding star of global terrorism.

WASHINGTON — Images of the wreckage of the helicopter left behind at Osama bin Laden's compound by U.S. forces have prompted speculation that the chopper is a secret, highly-modified version of the military's iconic Black Hawk.

The stricken aircraft, which commandos blew up at the scene, appears to be a long-rumored stealth helicopter, NBC News reported; a Black Hawk modified to reduce rotor noise and make it more difficult to detect by radar.

Pentagon officials have declined to comment as did Sikorsky, the helicopter's manufacturer.

Noise reduction can be accomplished by adding blades to the rotors and changing the way the pilot flies the chopper, such as flying in a manner to reduce the rotor's rpm, the report said.

As for reducing the likelihood of the aircraft chopper giving off infrared signals, Aviation Week pointed to an earlier helicopter prototype that had a complex exhaust system and fresh air ejectors to lessen the aircraft's heat signals.

If the modifications did reduce the helicopter's sound, the raid still was noisy enough to attract attention. A computer programmer,
Sohaib Athar
, was startled by the noise and posted a note to Twitter: "Helicopter hovering above Abbotabad at 1AM (is a rare event)."

"It really didn’t look like a traditional Black Hawk," the retired aviator told the Times, noting that it had "hard edges, sort of like an … F-117, you know how they have those distinctive edges and angles — that’s what they had on this one." The U.S. Army began using the standard Black Hawk in 1979.

The source added that the helicopter's windshield might have been specially coated to help evade radar detection, making it "very plausible" that pilots wearing night-vision goggles would have a harder time with visibility.

The apparent modifications might have played a role in the chopper's hard landing as well, the retired aviator told the Times, because the additions could have added several hundred pounds to the weight of the craft.

Photos of the downed helicopter sparked a flurry of speculation about the design in the days after the raid, as the sections that survived the blast looked unlike anything the military has openly acknowledged, the Times report noted.

The downed chopper was one of two Black Hawks that transported the commandos who carried out the raid from Bagram Air Base in Afghanistan to the Abbottabad, Pakistan compound.

The original plan to place a rappelling team on the roof with a second team dropping into the courtyard was jettisoned when one of the helicopters, its blades clawing at hot, too-thin air, had to put down hard. Both choppers landed in the courtyard, behind one ring of walls with more to go.

'Had to blow the helicopter'
After the team sent word to Washington that bin Laden — code name "Geronimo" — was killed in action, commandos quickly swept the compound, retrieving possibly crucial records on the operations of al-Qaida.

The strong Pakistani military presence in Abbottabad, a garrison city with a military academy near the compound, provided a cover of sorts for the Americans. No one would be particularly surprised to hear choppers flying at night.

But the team needed to destroy the chopper that gave them trouble. This renewed worries that Pakistani authorities — who were not told of the mission in advance — would discover the mission prematurely. Neighbors certainly noticed.

"We had to blow the helicopter," CIA Director Leon Panetta said, "and that probably woke up a lot of people, including the Pakistanis."

About 10 days before the raid, President Obama was briefed on the plan, NBC News reported. It included keeping two backup helicopters just outside Pakistani airspace in case something went wrong. But Obama felt that was risky. If the SEALs needed help, they couldn't afford to wait for backup.

He said the operation needed a plan in case the SEALs had to fight their way out. So two Chinooks were sent into Pakistani airspace, loaded with backup teams, just in case. One of those Chinooks landed in the compound after the Black Hawk became inoperable.

The raiders scrambled aboard the remaining Black Hawk and a Chinook, bin Laden's body with them, and flew to the USS Carl Vinson in the North Arabian Sea. The ground operation had taken about 40 minutes.

Only after the Americans left the area was Pakistan informed of what had happened on its territory.

Joint Chiefs Chairman Adm. Mike Mullen called Pakistani Army chief Ashfaq Kayani to tell him that an operation he had not known about was complete, a U.S. official told AP. Panetta called his Pakistani counterpart shortly afterward.

Mere hours after the operation, before most of the world knew bin Laden was found and killed, his body was buried at sea.

The Associated Press contributed to this report.

Video: Details of US stealth chopper ricochet around globe

>>>while the u.s. did gain a lot of intelligence during the raid, it accidentally gave away some as well. remember the initial report, one of the
black hawk helicopters
used in the raid failed and was destroyed by the departmenting navy s.e.a.l.s. it almost was all destroyed and then when the world of aviation saw the pictures of the
tail section
that was left intact on one of the compound walls, everybody realized this was nothing anyone had ever seen before. and it's widely reported now to be the world's first glimpse at the new stealth
blackhawk helicopter
program. most notable, the
tail rotor
, the unusual blades, the dish pan style covering on the mechanism designed to deflect electronic detection. they also fly much more quietly to enhance the element of surprise. the chinese are known to be in somewhat of a race to perfect the same technology, and while the pakistanis took away the big parts, some local children were seen walking around with the smaller pieces of the chopper as souvenirs.

An aerial view shows the residential area of Abbottabad, Pakistan, where Osama bin Laden was found and killed by U.S. commandos.
(Asif Hassan / AFP - Getty Images)
ShareBack to slideshow navigation

A general view of the town of Abbottabad, May 6. Bin Laden was living in a large house close to a military academy in this garrison town, a two-and-a-half hour-drive from the capital, Islamabad.
(Khaqan Khawer / EPA)
ShareBack to slideshow navigation

Supporters of Pakistani religious party Jamaat-e-Islami rally to condemn the killing of bin Laden, in Abbottabad on May 6.
(Aqeel Ahmed / AP)
ShareBack to slideshow navigation

A Pakistani woman photographs her daughter on May , at a gate of the compound where bin Laden was caught and killed.
(Aqeel Ahmed / AP)
ShareBack to slideshow navigation

School girls pass by armed Pakistani policemen guarding the sealed entrance to the compound in Abbottabad, May 5, in which bin Laden had been living.
(MD Nadeem / EPA)
ShareBack to slideshow navigation

A Pakistani police officer gestures at a checkpoint along a road leading to a house where bin Laden was captured and killed in Abbottabad. Area residents were still confused and suspicious about bin Laden's death, which took place before dawn on Monday.
(Anjum Naveed / AP)
ShareBack to slideshow navigation

Part of a damaged U.S. MH-60 helicopter lies the compound. The helicopter was destroyed by U.S. forces after a mechanical failure left it unable to take off.
(Reuters)
ShareBack to slideshow navigation

A still image from video obtained by ABC News shows blood stains in the interior of the house where bin Laden was killed.
(ABC News via Reuters)
ShareBack to slideshow navigation

Aerial views released by the Department of Defense show the area in Abbottabad in 2004, left, before the house was built, and in 2011, right.
(Department of Defense via Reuters)
ShareBack to slideshow navigation

Boys collect pieces of metal from a wheat field outside bin Laden's house, seen in the background, on May 3. People showed off small parts of what appeared to be a U.S. helicopter that the U.S. says malfunctioned and was blown up by the American team as it retreated.
(Anjum Naveed / AP)
ShareBack to slideshow navigation

An image from video seized from the walled compound of al-Qaida leader Osama bin Laden in Abbottabad, and released by the U.S. Department of Defense, shows Osama bin Laden watching TV. He is said to have spent his last weeks in a house divided, amid wives riven by suspicions. On the top floor, sharing his bedroom, was his youngest wife and favorite. The trouble came when his eldest wife showed up and moved into the bedroom on the floor below.
(Department of Defense via AP)
ShareBack to slideshow navigation

Editor's note:
This image contains graphic content that some viewers may find disturbing.

Timeline: A timeline of Osama bin Laden's life

Considered enemy No. 1 by the U.S., the Saudi millionaire is the perpetrator behind the Sept. 11, 2001, attacks. Click on key dates to learn more about the founder of al-Qaida, an international terror network.

JavaScript is required to view our full story experience.
Please enable JavaScript in your browser preferences.